Read mail message

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already indicate readOnlyHint=true, and the description adds meaningful behavioral context beyond that: it describes the response_format behaviors ('concise' vs 'detailed') and discloses that the detailed body is truncated by a configured limit. This goes beyond the annotations, though it could have mentioned error handling or idempotency.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is moderately sized and well-structured, starting with a one-line summary, then a usage note, then an Args list. Every sentence contributes value with no fluff, though it is slightly longer than the minimal needed.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given only two parameters and no output schema, the description adequately covers what the tool returns (headers and body), the output format choices, and how it relates to sibling tools. It provides enough information for an agent to invoke the tool correctly.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The input schema has zero property descriptions (0% coverage), but the description's Args section fully compensates. It explains message_id format (with/without angle brackets or 'id:' prefix) and the two response_format options with their effects. This adds substantial meaning beyond the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool returns a single message's headers and body, using a specific verb and resource. It also distinguishes itself from the sibling mail_read_thread by explicitly noting the difference between a single message and an entire conversation.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides explicit guidance on when to use this tool ('for one specific message') and names the alternative for conversations (mail_read_thread). It also includes parameter-specific usage details, such as how to format message_id and the two response_format options.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.